Magnetoionic control of perpendicular exchange bias

Voltage control of magnetism via ionic motion (magnetoionic control) is currently a thriving approach for low-power magnetic nanodevices. Recently, fast switching and high reversibility have been achieved for proton (H+)-based magnetoionic control in all-solid devices. In this work, the authors extend such (H+)-based magnetoionic control to a perpendicular exchange bias (EB) systems by functionalizing the ferromagnetic Co layer with an underlying antiferromagnetic NiO layer. They reveal the importance of an interfacial Pd layer for the existence of perpendicular EB in this system. Importantly, they demonstrate reversible (H+)-based magnetoionic control of remanence and coercivity in such a perpendicular EB system and thoroughly discuss the underlying mechanism.